Mid-oceanic ridge

The mid-ocean ridge (shown in red) winds its way between the continents

Mid-oceanic ridge data gathered by oceanographic surveys conducted by many nations led to the discovery that a great mountain range on the ocean floor virtually encircled the Earth. Called the global mid-ocean ridge, this immense submarine mountain chain -- more than 50,000 kilometers (km) long and, in places, more than 800 km across -- zig-zags between the continents, winding its way around the globe like the seam on a baseball. Rising an average of about 4,500 meters(m) above the sea floor, the mid-ocean ridge overshadows all the mountains in the United States except for Mount McKinley (Denali) in Alaska (6,194 m). Though hidden beneath the ocean surface, the global mid-ocean ridge system is the most prominent topographic feature on the surface of our planet.

Computer-generated detailed topographic map of a segment of the Mid-Oceanic Ridge.

Mid-oceanic ridge contains a rift through which red-hot magma is squeezed up from the mantle.